Turbo aero engine distributors are fixed vanes disposed in a circle and disposed in front of the vanes linked to the rotor, especially in low pressure turbo aero engines, and whose function is to ensure an appropriate correction of the flow of the gases of the motor so as to increase the yield of said motor.
In practice, these distributors are composed of juxtaposed sectors each extending onto an arc of a circle, and imperviousness plates extending between the sectors so as to prohibit any gas leaks as much as possible.
The purpose of the invention is to create a particular shape for distributor sectors: their radially outer edge is fitted on one side with a circular projection extending in an axial direction and on the other side with a circular projection extending in a radial direction: these projections known as overlays are intended to ensure the mounting of the distributor sectors in the housing of the turbo aero engine which for this purpose is provided with an axial lip against which the first projection rests, and a radial lip against which the second projection rests. However, it is impossible to make the projections enter the housings delimited by the lips by means of a single movement so that it is impossible to carry out a manual mounting as effected with distributor sectors having a simpler shape.
The invention relates to tools able to easily mount this type of distributor sectors in their locations of the turbo aero engine housing after having been picked up; this tool can also be used to dismantle this distributor by contrary operations, as shall be subsequently revealed in the remainder of this description.
To sum up, the invention concerns a tool for mounting a turbo aero engine distributor formed of adjacent arc of a circle shaped sectors in a turbine casing provided with two annular housings, the first of the housings situated on a tapered side of the casing being delimited by a first lip of the casing extending axially opposite the tapered side, the second housing situated on a flared side of the casing being delimited by a second lip of the casing extending radially towards the inside, the sectors including on a radially external portion a first projection engaged in the first housing and extending axially towards the tapered side when the distributor is mounted in the casing, and the second projection engaged in the second housing and extending radially towards the outside when the distributor is mounted in the casing, the tool being characterized by:
a circular plate, PA1 sector mounting units associated respectively with the distributor sectors and each including:
a sector support, PA2 a mechanism for suspending the sector support from the circular plate, PA2 and a mechanism for controlling tilting of the sector support, said mechanism being disposed between the sector support and the circular plate making it possible to slant the sector borne by the support.
In the currently retained embodiment, the suspension mechanism includes a pair of connecting rods joined to the sector support; one of the connecting rods is also joined to the plate and the other is also joined to a member common to all the mounting units of the tilting control mechanism.
A particularly simple tilting control mechanism includes a nut screwed onto a threaded spindle of the plate, and a crown rotating in the nut around the threaded spindle: this crown is actually said common member.
So as to start mounting, it is useful to lower a precise movement of the sector supports: for this purpose, the tool may include a plane on which the casing is laid and from which the plate is suspended by a lowering mechanism possibly consisting of a second nut screwed onto the threaded spindle and placed on a chuck of the base, the spindle sliding along the chuck with a rotation stoppage link.
The suspension of the sector supports needs to be flexible when introducing the projections of the sectors in the housings delimited by the lips of the casing, but this flexibility was previously not really favorable, especially when the previously arranged sectors had to be picked up by the supports: this is why it is preferable to add an articulation inhibition mechanism, possibly being released, which connects to the circular plate the projections joined to the latter and temporarily immobilizes them. A simple conception for this articulation inhibition mechanism is a spring-back return movement mechanism which imposes a tilting of the connecting rods radially towards the inside when it is released via the action of a spring, for example.
The tool may include a plane for laying the distributor sectors according to a disposition approximately identical to their mounting disposition in the casing: this makes it possible to manually assemble the distributor before its segments are picked up by the mounting units.
Finally, the tools can also facilitate the mounting of rotor wheels situated behind the distributors once the latter are mounted: this concerns elements, such as a retaining ring, whose effect is to retain the imperviousness segments placed in the casing close to the distributor and extending around the wheel of the rotor: thus, any risk of these sealing elements moving when inserting the wheel is eliminated. A stage preliminary to installation of the retaining ring can be carried out if blocks, able to move is a radial direction, are provided on the tool and disposed so as to press the sealing elements on the casing before the mounting units release the distributor sectors and the tool is withdrawn.